Stud welding is a technique similar to flash welding where a fastener or specially formed nut is welded onto another metal part, typically a base metal or substrate. The fastener can take different forms, but typically fall under threaded, unthreaded or tapped. The bolts may be automatically fed into the spot welder. Weld nuts generally have a flange with small nubs that melt to form the weld. Weld studs are used in stud welding systems.
Capacitor Discharge stud welding eliminates drilling, tapping, punching, riveting, gluing, and screwing; and is especially beneficial when working with thin gauge materials due to the absence of reverse-side marring or discoloration. This process is suitable for studs ranging in size from #4-40 (M3) thru 3/8-16 (M10). During the CD process, the capacitors are charged to a setting pre determined on the front of the power supply. The CD gun is loaded with a weld stud and pushed into the base material under spring pressure. The tip touches the workpiece which closes the electrical circuit. Upon trigger from the CD gun the capacitors are emptied, the stud and workpiece surface from a molten material and solidfy together forming a solid weld. The welding time for CD studs is approx 3 milliseconds.
It started in the 1940’s when a welder had to attach threaded fasteners onto ships in a naval shipyard. He did this by holding a stud flush against the base metal and welding a fillet around the base of the stud. This was a very slow process so he came up with the idea of holding the stud in an electrode holder and touching the end of the stud to the spot where it was to be welded on the base metal and quickly lifting the stud from the base plate drawing an arc and after a short welding time he pushed the stud down into the molten puddle that had formed during the arcing. This resulted in the extinguishing of the arc which in turn resulted in a contiguous weld between the base plate and the stud. This man realized that in order to obtain consistent results he would have to design a way to lift the stud a constant amount in order to have a constant arc length and a constant weld time. He came up with the idea of holding the stud in a chuck and using a solenoid to lift the stud away from the base plate which would create an arc and having a timer that would de-energize the solenoid after a predetermined amount of time. With the use of these modifications it was possible to achieve welding consistency.
Over the years welding stud manufacturers have made improvements to the stud welding process. On of which was the use of a solid aluminum flux ball attached to the weld base of the stud instead of the granular flux that bad been originally used. This was such an improvement over the granular flux, most stud manufacturers changed to the use of a solid flux over time.
Several standard handgun models are available from stock to accommodate routine applications, while automated production systems are available on a custom-designed basis for high volume applications.
Stud Welding & Fasteners, Inc. supplies CD stud welding equipment for a range of markets all over the United States, including the automotive, construction, and industrial, as well as original equipment manufacturers and building contractors. SWF offers externally threaded fasteners, shear connectors, concrete anchors, punching resistor studs, inserts, ports, pipe and cable hangers, weld studs and bosses, and the equipment used to apply, assemble, and weld stud fasteners. Give us a call at (800) 936-1948 for more information.